(Physically Unclonable 

As a term referring to “functions that cannot be physically duplicated,” it is an immutable function that cannot withstand any hacking attempt, and is the basis of IoT security solutions.
Since each semiconductor chip generates a different unique ID, It is called the fingerprint of the semicon.

It is not a method of generating and injecting a unique ID from the outside, but it is generated inside the semiconductor chip, so there is no risk of leakage of the encryption key, which is the core of IoT security. (See Figures (a) and (b))